在Android 7中的相机预览黑色

为了向后兼容,我使用了一个简单的Camera API 。 相机视图本身被一个imageview稍微覆盖,我的surfaceChanged这样做:

camera.setPreviewCallback((data, arg1) -> LiveView.this.invalidate()); camera.setPreviewDisplay(mHolder); camera.startPreview(); 

所有较旧的设备上工作正常。 我将预览大小设置为surfaceCreated较早的最大可用大小。 然而,在Android 7.1上,它突然变黑了(在Nexus 6和Moto X Play上,可能还有其他的 – 在不同的设备上)。 SurfaceView本身在Layout InspectorwillNotDraw = true )中是灰色的,但是VISIBLE (和硬件加速)。 奇怪的是,我仍然可以拍照,事件没有预览,预览callback中的数据包含一个图像。

同时我得到以下日志

 E/mm-camera: mct_pipeline_send_ctrl_events: Send Set Parm events E/QCamera2HWI: static void* qcamera::QCameraCbNotifier::cbNotifyRoutine(void*) : cb message type 32768 not enabled! E/QCamera2HWI: static void* qcamera::QCameraCbNotifier::cbNotifyRoutine(void*) : cb message type 32768 not enabled! D/QCameraParameters: setSnapshotSkipHint: preview hint 3 fps 15.019738 

有没有人在Android 7中经历了一个完全黑色的图像? 有没有简单的修复? (如直接绘制数据的内容?)

Solutions Collecting From Web of "在Android 7中的相机预览黑色"

黑屏出现,因为你没有Android 7设备的相机权限

转到设置 – >应用程序 – >select您的应用程序 – >权限 – >启用相机的权限和检查

你也可以在你的代码中处理这个

为清单添加以下权限

 <uses-permission android:name="android.permission.CAMERA" /> 

为了获得许可,你可以这样打电话。

 ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.CAMERA}, MY_PERMISSIONS_REQUEST_CAMERA); 

检查访问摄像头的权限

 if (ContextCompat.checkSelfPermission(this, Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED) { } 

现在callback,如果用户已经执行任何操作。

 @Override public void onRequestPermissionsResult(int requestCode, String permissions[], int[] grantResults) { switch (requestCode) { case MY_PERMISSIONS_REQUEST_CAMERA: { Log.i("Camera", "G : " + grantResults[0]); // If request is cancelled, the result arrays are empty. if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) { // permission was granted, yay! Do the // contacts-related task you need to do. openCamera(); } else { // permission denied, boo! Disable the // functionality that depends on this permission. if (ActivityCompat.shouldShowRequestPermissionRationale (this, Manifest.permission.CAMERA)) { showAlert(); } else { } } return; } // other 'case' lines to check for other // permissions this app might request } } 

这里是完整的例子

  import android.Manifest; import android.app.Activity; import android.app.AlertDialog; import android.content.Context; import android.content.DialogInterface; import android.content.Intent; import android.content.SharedPreferences; import android.content.pm.PackageManager; import android.net.Uri; import android.os.Bundle; import android.provider.Settings; import android.support.v4.app.ActivityCompat; import android.support.v4.content.ContextCompat; import android.support.v7.app.AppCompatActivity; import android.support.v7.widget.Toolbar; public class MainActivity extends AppCompatActivity { public static final int MY_PERMISSIONS_REQUEST_CAMERA = 100; public static final String ALLOW_KEY = "ALLOWED"; public static final String CAMERA_PREF = "camera_pref"; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar); setSupportActionBar(toolbar); if (ContextCompat.checkSelfPermission(this, Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED) { if (getFromPref(this, ALLOW_KEY)) { showSettingsAlert(); } else if (ContextCompat.checkSelfPermission(this, Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED) { // Should we show an explanation? if (ActivityCompat.shouldShowRequestPermissionRationale(this, Manifest.permission.CAMERA)) { showAlert(); } else { // No explanation needed, we can request the permission. ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.CAMERA}, MY_PERMISSIONS_REQUEST_CAMERA); } } } else { openCamera(); } } public static void saveToPreferences(Context context, String key, Boolean allowed) { SharedPreferences myPrefs = context.getSharedPreferences (CAMERA_PREF, Context.MODE_PRIVATE); SharedPreferences.Editor prefsEditor = myPrefs.edit(); prefsEditor.putBoolean(key, allowed); prefsEditor.commit(); } public static Boolean getFromPref(Context context, String key) { SharedPreferences myPrefs = context.getSharedPreferences (CAMERA_PREF, Context.MODE_PRIVATE); return (myPrefs.getBoolean(key, false)); } private void showAlert() { AlertDialog alertDialog = new AlertDialog.Builder(this).create(); alertDialog.setTitle("Alert"); alertDialog.setMessage("App needs to access the Camera."); alertDialog.setButton(AlertDialog.BUTTON_NEGATIVE, "DONT ALLOW", new DialogInterface.OnClickListener() { public void onClick(DialogInterface dialog, int which) { dialog.dismiss(); finish(); } }); alertDialog.setButton(AlertDialog.BUTTON_POSITIVE, "ALLOW", new DialogInterface.OnClickListener() { public void onClick(DialogInterface dialog, int which) { dialog.dismiss(); ActivityCompat.requestPermissions(MainActivity.this, new String[]{Manifest.permission.CAMERA}, MY_PERMISSIONS_REQUEST_CAMERA); } }); alertDialog.show(); } private void showSettingsAlert() { AlertDialog alertDialog = new AlertDialog.Builder(this).create(); alertDialog.setTitle("Alert"); alertDialog.setMessage("App needs to access the Camera."); alertDialog.setButton(AlertDialog.BUTTON_NEGATIVE, "DONT ALLOW", new DialogInterface.OnClickListener() { public void onClick(DialogInterface dialog, int which) { dialog.dismiss(); //finish(); } }); alertDialog.setButton(AlertDialog.BUTTON_POSITIVE, "SETTINGS", new DialogInterface.OnClickListener() { public void onClick(DialogInterface dialog, int which) { dialog.dismiss(); startInstalledAppDetailsActivity(MainActivity.this); } }); alertDialog.show(); } @Override public void onRequestPermissionsResult (int requestCode, String permissions[], int[] grantResults) { switch (requestCode) { case MY_PERMISSIONS_REQUEST_CAMERA: { for (int i = 0, len = permissions.length; i < len; i++) { String permission = permissions[i]; if (grantResults[i] == PackageManager.PERMISSION_DENIED) { boolean showRationale = ActivityCompat.shouldShowRequestPermissionRationale (this, permission); if (showRationale) { showAlert(); } else if (!showRationale) { // user denied flagging NEVER ASK AGAIN // you can either enable some fall back, // disable features of your app // or open another dialog explaining // again the permission and directing to // the app setting saveToPreferences(MainActivity.this, ALLOW_KEY, true); } } } } // other 'case' lines to check for other // permissions this app might request } } public static void startInstalledAppDetailsActivity(final Activity context) { if (context == null) { return; } final Intent i = new Intent(); i.setAction(Settings.ACTION_APPLICATION_DETAILS_SETTINGS); i.addCategory(Intent.CATEGORY_DEFAULT); i.setData(Uri.parse("package:" + context.getPackageName())); i.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK); i.addFlags(Intent.FLAG_ACTIVITY_NO_HISTORY); i.addFlags(Intent.FLAG_ACTIVITY_EXCLUDE_FROM_RECENTS); context.startActivity(i); } private void openCamera() { Intent intent = new Intent("android.media.action.IMAGE_CAPTURE"); startActivity(intent); } } 

像@apk之前所说的,黑屏出现是因为你没有在你的代码中处理权限。 如果您正在使用targetSdkVersion 23 (及更高版本),则必须在运行时向用户请求权限。

以前的评论解释了如何通过SDK的操作直接解决它,但我更喜欢使用一个伟大的第三方库这些情况: 卡美米/德克斯特

检查Android运行时相机的权限

如果不允许权限,相机将显示空白屏幕。

更多细节 :

https://inthecheesefactory.com/blog/things-you-need-to-know-about-android-m-permission-developer-edition/en